Integrated optical devices for directly processing optical signals have become of greater importance as optical fiber communications increasingly replace metallic cable and microwave transmission links. Integrated optical devices can advantageously be implemented as silicon optical circuits having compact dimensions at relatively low cost. Silicon optical circuits employ integrated waveguide structures formed in a silicon layer of a silicon on insulator (SOI) substrates, to form a silicon photonic chip.
In some applications, the optical signal is injected in/extracted from the photonic chip in a near perpendicular fashion, with respect to the photonic chip substrate plane, by means of optical grating couplers formed in the silicon photonic chip for input-output of the photonic signal. When using the silicon substrate in such a coupling fashion, such as when coupling to an optical fiber, the optical fiber is mounted in near perpendicular fashion.